Phytoestrogenic Effects of Fungally Induced Isoflavonoids in Legumes
Food and Feed Safety Research
2012 Annual Report
1a.Objectives (from AD-416):
Utilize microbial elicitors of isoflavonoid production in manipulation of isoflavonoid levels. Test individual or combinations of isoflavonoid compounds induced by microbial elicitors for phytoestrogenic effects in animal systems. Test effects of phytoalexins using in vitro cell systems for PPAR transcriptional activity, adipocyte differentiation, and obesity related gene expression. Evaluate in vivo gene expression from tissue samples from ongoing experiments.
1b.Approach (from AD-416):
Estrogenic and antiestrogenic activities of isoflavonoids isolated from soybean tissues/organs will be analyzed by determining their ability to support in vitro and in vivo growth of several different cancer cell lines. Compounds will be screened for estrogen activity in assays using breast cancer cells incorporating an estrogen dependent promoter coupled with a luciferase reporter gene. Compounds will be assayed in order to determine synergistic effects and to measure estrogenic potency. Also, compounds will be screened for estrogen receptor binding and breast cancer proliferation. Anitestrogenic activity will be determined for all compounds. Antiestrogenic compounds will be tested in vivo using a mouse model system with different cancer cell lines, including breast, ovarian, and prostate cells.
Our research identified the hormonal activity of novel plant compound found in soy (Glyceollins 1-3). In contrast to the previously described compounds that have estrogenic (effect of the female hormone estrogen) activity found in soy (namely genistein and daidzein) the glyceollins exhibit antagonistic (the consequence of one chemical counteracting the effects of another chemical) or anti-estrogenic activity in breast cancer cells. Inducible compounds in soybean seed known as glyceollins were purified and used in several animal cell assays, demonstrating that these compounds block the growth of breast cancer cells and indicating their potentially useful activity. Also, 35 kg of glyceollin-enriched soy protein isolate was produced with the assistance of Solae Corporation. Two separate feeding studies examining the effects of the glyceollin-enriched soy protein isolate on breast cancer inhibition are underway at both Wake Forest University in Winston-Salem, NC, and Tulane University School of Medicine in New Orleans, LA. We have established the ability of glyceollins to significantly suppress growth of breast cancer cells in mice. It was shown that glyceollins were better at controlling cancer than the currently used drug tamoxifen. We found that the glyceollins also inhibited growth of human prostrate cancer cells LNCaP. In the last year of our research, we have further examined the potential of the soy glyceollins and effects on cancer. Building upon the specific targeting activity of glyceollins on biochemical pathways we have begun to investigate their activity in difficult to treat estrogen receptor-negative breast cancer cell systems. Ongoing studies have demonstrated that the glyceollins can suppress cancer growth and metastasis (spreading to other organs) of estrogen receptor-negative cancer. These data provide evidence that the glyceollins may represent a more universally useful anti-cancer agent when compared to commercially available compounds.